GRIFFITHS — THE GRAMA GRASSES. 



355 



consisting of one spikelet, the rachis prolonged 1 to 2 mm. beyond; spikelet 2-flowered, 

 the lower floret perfect, the upper reduced to a 3-awned rudiment; glumes minutely 

 hispidulous on the keel, acuminate, the first 2 to 3 mm., the second 4 to 5 mm. long, 

 very short-awned or merely acuminate; lemma ovate, indistinctly 3-nerved, especially 

 below, 3-toothed at the apex, rarely awned; palet 2-nerved with 2 short awns at the 

 apex; rudiment consisting of 3 sca- 

 brous awns about 7 mm. long, upon 

 a naked stipe 3 mm. long; caryopsis 

 not seen. (Figure 19.) 



This species is common upon the 

 highlands of central Mexico, espe- 

 cially from Hidalgo to Oaxaca, and 

 extends far into Guerrero and west- 

 ern Jalisco. It is well represented 

 in herbaria by Pringle 7482, 870, 

 and 9573, and Nelson 1842, which 

 are typical. Miguel Bang's no. 1307 

 in Plantae Bolivianae, from Sorata, 

 Bolivia (distributed by Britton and 

 Rusby), and Schop's no. 740 are both 

 immature. The latter probably be- 

 longs here, but the former is doubt- 

 fully referred to this species. 



HERBARIUM SPECIMENS. 



Mexico: Pringle 9573, El Salto; 8708, 

 near Jojutla; 4792, Los Sedas, 

 Oaxaca. Nelson 1842, Domin- 

 guillo; 1542, Valley of Oaxaca. 

 Conzatti & Gonzalez 265, Los 

 Sedas. Schott 740, Yucatan. 



PENTARRHAPHIS H. B. K. 



Pentarrhaphis H. B. K. Nov. Gen. 

 &Sp. 1: 177. pi. 60.1816. A mono- 

 typic genus based upon P. scabra. 



Polyschistis Presl, Rel. Haenk. 

 1: 294. pi. 41. f. 12-18. 1830. Based 

 upon P. paupercula. 



StrombodurusWiWd.; Steud.Nom. 

 Bot. ed. 2. 2 : 299. 1841. This is 

 listed as a synonym of Pentar- 

 rhaphis, and the single species S. 

 gracilis Willd. is referred (page 647) 

 to Pentarrhaphis scabra H. B. K. 

 (The initial letter of the latter 

 generic name is misprinted "D".) 



Species with small, woolly spikes consisting of 2 spikelets, one of these sometimes 

 aborted, approximate on a rachis ending in a forked or bifid prolongation; first glume 

 of each spikelet reduced to scarcely more than a straight awn; these together with 

 the bifid rachis appearing like a cluster of awns at the base of the spikelet; spikelets 

 2-flowered. 



Fig. 19. — Triaena j-vmcea. a, Spikelet; &, c, lemma and palet 

 of first floret; d, rudiment, a, Scale 5; b-d, scale 10. From 

 Griffiths 8122. 



